ABSTRACT Luminescent ferroelectrics hold great promise for optoelectronic devices owing to their intrinsic coupling between polarization and optical properties. However, achieving luminescence that is directly and robustly controlled by the ferroelectric state rather than as an indirect consequence of temperature remains a fundamental challenge. Here, we report the first reentrant luminescent ferroelectric, a lead‐free hybrid antimony halide, (3,3‐difluoropyrrolidinium) 2 SbCl 5 ((C 4 H 8 F 2 N) 2 SbCl 5 , DC ), that overcomes this challenge by integrating broadband emission with a re‐entrant ferroelectric phase transition sequence. DC displays two Curie points ( T C1 = 149 K and T C2 = 253 K), giving rise to a wide ferroelectric window (∼104 K). Critically, within this intermediate polar phase, the material exhibits intense remanent polarization ( P r ≈ 7.3 µC cm −2 ) that directly couples with an anti‐thermal quenching behavior of photoluminescence (ΔE a ≈ 59 meV) in contrast to conventional thermal quenching in the paraelectric phases. First‐principles calculations reveal that a ligand‐to‐metal charge transfer underpins the self‐trapped exciton emission, while the polar symmetry modulates radiative pathways. This “polarity‐gated” luminescence control, which operates independently of conventional temperature gating, provides an optical ON/OFF switching mechanism defined by symmetry and polarization. Our findings demonstrate a new material platform and design paradigm for multi‐stimuli‐responsive optoelectronics, uniting reentrant ferroelectricity with broadband emission.
Jiao et al. (Mon,) studied this question.